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Aiiwatani Tomae Japanese Natural Whetstone (JNAT) – Koppa #023

Aiiwatani Tomae Japanese Natural Whetstone (JNAT) – Koppa #023

$145.00 USD
$145.00 USD
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dimensions

(Sides) 16mm x 50mm x 80mm x 45mm x 50mm X (thickness) 25mm

Aiiwatani Tomae Japanese Natural Whetstone (JNAT) – Koppa 

Overview & Sharpening Characteristics

Mine & Strata: Aiiwatani (相岩谷産) Tomae.

Working Face: Clean, uniform golden-buff Kiita tone with a very consistent surface texture. 

Function: Excellent finisher for high-carbon kitchen cutlery, straight razors, or pocket knives. Offers smooth feedback, rapid swarf production with a light nagura or diamond plate, and leaves a refined, hazy kasumi contrast on clad steels with a crisp, toothy micro-bevel.

Condition & Flaws
Irregular Perimeter (Koppa): The stone has an irregular, non-rectangular shape with angled, natural edge cuts. There is a tiny line and off-color spot right at the corner - It does not seem to hinder the sharpening process and returned no negative feedback when tested.

Side Void & Fracturing: two minor chips along the rim - can be easily chamfered down when dressing the stone prior to first use.  

Under-Side/Base Chipping: Edge chipping and minor stepped flaking on the base and along the chamfer line of the back. These do not impact the stability of the stone at all. 

Thickness & Backing: The stone has moderate thickness with a raw, oxidized underside. All sides and back have been sealed with lacquare. 

care instructions

1. Preparation & Water Management
Splash-and-Go Only: Never soak your natural finishing stone in a water bath. Prolonged submersion softens the natural binders and risks cracking or delamination along natural mineral lines.
Surface Wetting: Mist or splash clean water onto the working face just before sharpening. Add water sparingly throughout your session to maintain a slick working surface.
Bench Placement: Place the stone on a non-slip rubber base or a dedicated wooden stone holder with gentle clamping pressure.
2. Slurry Generation & Sharpening
Soft to Medium Stones (Hardness 2.5–3.5): These stones naturally release their own slurry under light blade pressure. Let the auto-generated mud do the work; do not wash it away mid-session.
b Use a diamond plate (such as an Atoma 1200), a clean Tomo Nagura, or a Mikawa Nagura to raise a thin, milky slurry in 5 to 10 light circular passes before laying your blade flat.
Pressure & Technique: Maintain light, even pressure. Allow the semi-rounded silica particles in the slurry to break down naturally—this self-refining action creates the signature toothy edge and cloudy kasumi finish.
Slurry Thickness: If the mud becomes too sticky or pasty, add a few drops of water. If it is too thin, work the stone lightly to concentrate the abrasive particles.
3. Cleaning, Drying & Long-Term Care
Rinse Clean: When finished, gently rinse off steel swarf and residual slurry using room-temperature tap water. Do not use dish soap, detergents, or hot water.
Air Dry Indirectly: Wipe the stone dry with a clean towel and allow it to dry completely at room temperature, away from direct sunlight, heating vents, fans, or freeze-thaw cycles.
Storage: Store the completely dry stone flat on a shelf in a climate-controlled room. Avoid enclosing a damp stone in an airtight plastic box.
Edge Lapping: Keep the working surface flat by lightly dressing it with a fine diamond plate (Atoma 1200 or 400) under running water when dish patterns begin to form. Chamfer the outer top perimeter edges lightly to prevent edge chipping during blade passes.

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